Mimi, I am not positive about this but I believe you can dispute a credit card charge even after it's shown up on your bill--that's the whole point of the credit card dispute process. It's not like having a check cashed and now irrevocable. You file a dispute with your CC company saying you did not get what you ordered.
I'd try to return it for a FULL refund and find someone easier to work with, myself.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks